Amazon's bestselling MP3 album of the year was legally available as a free download on filesharing networks.

Proving either that market economics are complicated or Nine Inch Nails fans are crazy, Trent Reznor's Ghosts I-IV topped Amazon's list of 2008 sellers, beating Coldplay, Snow Patrol and Keane. The double-album was available for purchase at Amazon, direct from NIN, or as a free, Creative Commons-licensed download on major P2P networks.

Ghosts I-IV was a surprise release in March, announced without warning on the Nine Inch Nails website. Forgoing record labels, Reznor used independent licensing company Tunecore to make the 36 tracks available on Amazon – paying just $38 for the service. By selling special versions of the album, Ghosts I-IV generated some $1.6m (£1m) in revenue in its first week.

Other winners in Amazon's year-end MP3 album charts were Coldplay's Viva La Vida, Death Cab for Cutie's Narrow Stairs, the Mouldy Peaches-studded soundtrack to Juno, and 3 Doors Down's self-titled album. Radiohead's In Rainbows, which was also available as a free, legal download, was ranked No 8.

Buoyed by his success with Ghosts I-IV, Reznor's follow-up was again free, without even the need for P2P. The Slip is available as a direct download from the NIN site.

More recently, Reznor made available over 400GB of high-definition live NIN footage, inviting fans to edit the material themselves. Though he referred coyly to "a shadowy group of subversives" and "lacking security", this is presumably the raw footage from NIN's aborted live DVD project. So yes, it is, inevitably, free.